INFO sip:bob@one.example.com SIP/2.0
Via: SIP/2.0/UDP sip.example.com;branch=7c337f30d7ce.1
  ;maddr=239.128.16.254;ttl=16
Via: SIP/2.0/UDP mouse.wonderland.com
From: Alice <sip:alice@wonderland.com>;tag=1
To: Bob <sip:bob@example.com>
Call-ID: 602214199@mouse.wonderland.com
CSeq: 1 INVITE
Contact: Alice <sip:alice@mouse.wonderland.com>
Authentication-Info: 00000000000000000000000000000  a=
Subject: SIP will be discussed, too
Content-Length: 0